is that without any other specification (Moroccan Arabic, Lebanese Arabic, Syrian Arabic...), Arabic means what is known as Modern Standard Arabic (MSA), which only has three vocalic sounds ([a], [i], [u]), matching with the Arabic pronunciation passed on by the Quran.

Even if some Arabic speakers, when speaking in their Arabic dialects, pronounce ['lejla] (LAY-la, LAY rhyming with day or may), ['lela] (LEH-la) or ['lila] (LEE-la), those are not THE correct Arabic pronunciations (['lajla], LY-la, LY rhyming with my or by). Strictely, ['lejla] and ['lela] can't be correct MSA pronunciations because there is not [e] sound in its repertoire.